1. Field of the Invention
The present invention relates to a pin-type photovoltaic device comprising a silicon non-single crystal semiconductor material, a method of producing the devices, and a generating system using the same. Particularly, the present invention relates to a pin-type photovoltaic device in which the band gap in an i-type layer is changed, and a method of depositing the photovoltaic device by a microwave plasma CVD process. The present invention also relates to a generating system using the photovoltaic device.
2. Related Background Art
Conventional pin-structure photovoltaic devices each comprising a silicon non-single crystal semiconductor material include a photovoltaic device comprising, an i-layer which contains silicon atoms and carbon or germanium atoms, and in which the band gap is changed. Examples of proposals for such a photovoltaic device include the following:
(1) "Optimum deposition conditions for a-(Si,Ge):H using a triode-configurated rf glow discharge system", J. A. Bragangnolo, P. Littlefield, A. Mastrovito and G. Storti, Conf. Rec. 19th IEEE photovoltaic Specialists Conference, 1987, pp. 878-883; PA1 (2) "Efficiency improvement in amorphous-SiGe:H solar cells and its application to tandem type solar cells", S. Yoshida, S. Yamanaka, M. Konagai and K. Takahashi, Conf. Rec. 19th IEEE Photovoltaic Specialists Conference, 1987, pp. 1101-1106; PA1 (3) "Stability and terrestrial application of a-Si tandem type solar cells", A. Hiroe, H. Yamagishi, H. Nishio, M. Kondo, and Y. Tawada, Conf. Rec. 19th IEEE Photovoltaic Specialists Conference, 1987, pp. 1111-1116; PA1 (4) "Preparation of high quality a-SiGe:H films and its application to the high efficiency triple-junction amorphous solar cells", K. Sato, K. Kawabata, S. Terazono, H. Sasaki, M. Deguchi, T. Itagaki, H. Morikawa, M. Aiga and K. Fujikawa, Conf. Rec. 20th IEEE Photovoltaic Specialists Conference, 1988, pp. 73-78; PA1 (5) U.S. Pat. No. 4,816,082; PA1 (6) U.S. Pat. No. 4,471,155; and PA1 (7) U.S. Pat. No. 4,782,376. PA1 (8) "A novel design for amorphous silicon alloy solar cells", S. Guha, J. Yang, A. Pawlikiewicz, T. Glatfelter, R. Ross, and S. R. Ovshinsky, Conf. Rec. 20th IEEE Photovoltaic Specialists Conference, 1988, pp. 79-84; and PA1 (9) "Numerical modeling of multijunction, amorphous silicon based P-I-N solar cells", A. H. Pawlikiewicz and S. Guha, Conf. Rec. 20th IEEE Photovoltaic Specialists Conference, 1988, pp. 251-255.
Examples of theoretical research on the characteristics of a photovoltaic device in which the band gap changes include the following:
In such conventional photovoltaic devices of the prior art, a layer in which the band gap changes is inserted into the p/i and n/i interfaces in order to prevent the recombination of photo-excited carriers in the vicinity of each of the interfaces, and increase the open-circuit voltage and the hole carrier range.
With respect to a conventional photovoltaic device which contains silicon and carbon atoms and in which the band gap changes, it is necessary to improve the practical performance and reliability, and further prevent the recombination of photo-excited carriers. It is also necessary to increase the open-circuit voltage and the hole carrier range.
The conventional photovoltaic device also has the problem that the conversion efficiency deteriorates when weak light is applied thereto.
The conventional photovoltaic device further has the problem that since there is a strain in the i-type layer strained, the photoelectric conversion efficiency deteriorates when the layer is annealed under vibration or the like.